hello, yes berring buddies can be added to your hubs very easily...
pop off the dust cap that comes stock with the trailer you are buying... Find out the hub diameter (where the berrings go in, or what the dust cap that you just popped off fits into). Purchase the appropriate berring buddies.
Etrailer.com or Prinessauto.ca are great places to buy berring buddies for a good price. Once they arrive, get a small pieces of wood, like 6 inch cut of 2 x 4. Place berring buddy onto hub, first put a light bead of greece on the inner lip of the berring buddy. Now place the piece of wood on the outside of the berring buddy and lightly tap it with the hammer until the berring buddy is full seated.
Pump it up with greece. You will see the spring assembly of the berring buddy pushing outward toward you as you pump. Once that spring is 3/4 or a bit more compressed, let off. If you are having trouble disconnecting greece gun from zerc on the berring buddy get a flat head screwdriver and light pry the attachment off the zerc. Dont use too much force.
Now dont forget to put on the rubber seal which keeps water out when you launch and dont forget to greece the berring buddy periodically. You know that when the spring is sinking into the berring buddy that you should put some more grease in it. I generally pump them up at the beginning of the season, mid way through and at the end when I put away for winter storage... I hope this helped.
PS - If the berring buddy goes on too loose initially, take it off by very lightly tapping around the berring buddy in a circualar motion. It may take a while but just work it. Then give the hub a few short, solid hits with a hammer (not too hard), which will give the berring buddy a tighter fit when you refit it. What you're doing is very slightly warping the outside of end of the hub, so its not a perfect circle, but slightly off, which has no impact on the inner berrings, but allows the berring buddy to fit in a lot more snug. I have used this method on a friend's trailer. He kept loosing a berring buddy on one side.. it works very well.
Did you end up buying the boat and trailer??? If so , post some pics. lets see her...
cheers